RFID is a communication technology implementing a radio signal to identify a specific target and read/write related data. No physical or optical contact is needed between the specific target and a data reading system applying the RFID technology. As a result, data read/write speed of the data reading system is much faster than that of a traditional bar-code device. Considering the RFID technology is widely applied to fields of logistics management, public consumption, identification and smart homes and offices and greatly improves user convenience, many companies are successively investing huge research and develop budgets on the RFID technology.
An RFID tag is classified into active and passive types according to whether a chip is provided with an internal power supply. Taking a passive RFID tag as an example, an antenna of the RFID tag receives a radio signal transmitted from an RFID reader within a specific distance, and power needed by a chip circuit is provided by a received radio wave. Once started, the chip circuit of the RFID tag automatically interprets the signal received by the antenna and selectively provides data demanded by the RFID reader in the form of a radio signal.
Concerning security, the present RFID tag is generally classified into open and closed types. Any RFID reader is capable of accessing the data stored in an open RFID tag, such as an identification number of the tag, or an origin and a date of manufacture of goods to which the tag is attached. The open type of RFID tag is usually applied to a logistics management and a library system with a relatively low security requirement. A possessor of the chip can encrypt the data stored in the tag to increase barriers preventing abuse of the data; however, the measure does not stop an illegal reader from accessing the data stored in the tag. Moreover, once an encryption method of the data stored in the tag is decrypted, other tags applying the same encryption method are also exposed to danger.
In contrast, a protection or verification mechanism is provided in an RFID tag of a closed system. In other words, the RFID reader needs to pass an authentication procedure provided inside the tag in order to read/write the data stored in the tag. For example, after obtaining the identification number of the tag, the RFID reader applies a specific encrypting mechanism to encrypt the identification number and transmits the encrypted identification number to the tag. The tag decrypts the encrypted identification number via a decrypting mechanism corresponding to the encrypting mechanism and verifies whether the decrypted result is correct. When the decrypted result is correct, the RFID reader is then allowed to access the data stored in the tag. As a result, software and hardware of the RFID tag and the RFID reader device are specially designed and even a new circuit, such as an encrypting or a decrypting circuit, is added.
The closed tag and reader are generally applied to an identification card system and a traffic pre-paid card system, in which the data is strictly controlled. The closed RFID system can provide a relatively better data protection; however, cost of the closed RFID system is much higher than that of the open RFID system, and is a heavy burden with respect to users that need to purchase and maintain a great deal of RFID devices and RFID tags.
In view of the foregoing issues, the encrypting mechanism of the reader corresponding to the decrypting mechanism of the tag need be built inside the reader/tag in advance. Furthermore, in order to reduce cost, circuits and functions are usually unchangeable, and cannot be reset or revised by an end-user. When the RFID tag is purchased, the encrypting/decrypting algorithm cannot be adapted or changed as desired by an end-user. Therefore, the readers/tags produced by different manufactures are incompatible with one another and cannot operate interchangeably, resulting in great limitations and user inconveniences.